Resin-treated regenerated cellulose textile material and method of making the same



"May 24, I955 STIF'F'NESS MEAN FLEXURAL RIGID/TV MATERIAL AND METHOD OFMAKING THE SAME 2 Sheets-Sheet l D. BURKS. JR RESIN-TREATED REGENERATEDCELLULOSE TEXTILE Filed June 28, 1952 2 4 5 WET-HOED/NG TIME HOURS kFIGJ h 9 m i I \1 k :9. w; E i; I 5 I500 1: 2 J Lu LL 0.

1 i a E u 3 m k. g Li (I, 1000 c k v, z w m E 2 u a m E n E q k LL F/GZ/o 20 so RES/N APPLIED r0 FABRIC -PR c/5/vr moo 500 Q INVENTOR w fi? /oDANA BURKSJJR. r Byfi May 24, 1955 RESIN-TREATED REG BURKS. JR

ENERATED CELLULOSE TEXTILE Filed June 28, 1952 ST/FFNEES MEAN FLEXURALRIGID/TY 2 Sheets-Sheet 2 PREI//0U$ COMMON PRACTICE NEW PROCEDURE BASEFABR/C l0 20 RES/N APPL IEO TO FABRIC PER CENT WARP SHR/NKAQE PER CENTINVENTOR \mx X Q PREVIOUS COMMON PRACTICE I -"--NEW PROCEDURE WETHOLD/N6 TIME .3 HOURS ST/FFNESS OF UNTREA TED BASE FABR/C k E u S z i kUnited States Patent RESIN-TREATED REGENERATED CELLULOSE TEXTILEMATERIAL AND METHOD OF MAK- ING THE SAME Dana Burks, Jr., East Walpole,Mass, assignor to The Kendall Company, Boston, Mass, a corporation ofMassachusetts Application June 28, 1952, Serial No. 296,226

14 Claims. (Cl. 117--139.4)

The present invention relates to the finishing of regen erated cellulosetextile fabrics and more particularly to a novel regenerated cellulosetextile fabric treated with synthetic resin precondensates, and themethod pf making the same.

Although regenerated cellulose fabrics have enjoyed considerablecommercial success, they suffer from deficiencies which have seriouslylimited their utility. Such fabrics shrink excessively in laundering andbecause the shrinkage is progressive, cannot be satisfactorilystabilized by compressive shrinking methods, such as the Sanforizing"process used on high-quality cotton fabrics. In light, open-weavefabrics for use as curtains this shrinkage may amount to as much as 15%.Even in heavier weight, more closely woven constructions suitable forouter wear, these fabrics shrink from to Moreover, in outerwear fabricsan extremely desirable property is high resiliency, or the capacity torecover readily from wrinkling or creasing, and regenerated cellulosefabrics do not possess this property to any appreciable degree.

It has been well known in the art of finishing regenerated cellulosetextile fabrics that the tendency of the fabric to shrink in launderingcould be reduced and that its capacity to recover from wrinkling orcreasing could be increased by impregnating the fabric with a solutionor dispersion of a synthetic resin precondensate and a polymerizationcatalyst, and then curing the resin on the fabric. The improvement ofthe fabric with respect to dimensional stability and ability to recoverfrom creasing is approximately proportional to the amount of resinapplied. However, under conventional processing conditions, as theweight percentage of applied resin is in creased to the point at whichthe regenerated cellulose contains an amount of the resin precondensatewithin the range from about to about 35% on a weight basis, it has beenfound that the stiffness of the fabric sharply increases to anobjectionable level, and other important properties of the fabric, suchas tensile strength and elongation, are adversely affected. Theresulting fabric is totally unsuited for ordinary textile uses.

It is the object of my invention to provide a method of resin-treatingregenerated cellulose fabrics whereby the amount of resin prccondensateapplied to the fabric may be significantly increased beyond the levelwhich has hitherto been feasible.

My invention is based on my surprising discovery that if a regeneratedcellulose fabric, impregnated with a conventional polymerizationcatalyst and an aqueous solution of a synthetic resin precondensate iskept wet without substantial drying, following its impregnation with theresin solution and prior to the drying and curing of the fabric, for aperiod of time exceeding about 10 minutes, the amount of resinprecondensate which may be applied to the fabric may be substantiallyincreased beyond solution retained by the fabric.

the point at which, in the absence of my wet-holding step, the curedfabric would be objectionably stiff and brittle.

The resins which I have found satisfactory for use in my process arewater-soluble essentially monomeric precondensates selected from thegroup consisting of dimethylol urea, the lower alkylolmelamincs, thelower alkyl ethers of dimethylol urea and the lower alkyl ethers of thelower alkylolmelamines.

Any of the conventional, readily cold-water soluble polymerizationcatalysts are suitable for use in my process. Among such catalysts arezinc chloride, diammonium hydrogen phosphate, ammonium chloride,ammonium sulfate, acetic acid, and oxalic acid. The choice of theparticular catalyst is dependent on the resin employed and willordinarily be determined by the recommendation of the resin supplier. Iprefer to use an acidforrning catalyst, e. g. zinc chloride or ammoniumsalts of the mineral acids, rather than an acid itself.

The textile material to be treated in accordance with the invention maybe in the form of webs or bats or woven, unwoven, knitted or other rayonconstructions. Fabrics containing a mixture of fibers of regeneratedcellulose and other natural or synthetic fibers may be used. Both warpand weft may contain or consist of regenerated cellulose, or one ofthese may be formed entirely or partly of other material such as cotton,cellulose acetate, or nylon. The term regenerated cellulose as usedherein is intended to include regenerated cellulose whether made by theviscose or cuprammonium process. The fabric to be treated may first bethoroughly bottomed by scouring in the usual manner to remove sizing andother foreign material. After the bottoming treatment, the fabric isdried, preferably while framed to its original greige dimensions.

In carrying out my process, I first impregnate the fabric with anaqueous solution of the resin precondensate and a conventional coldwater soluble polymerization catalyst. Following impregnation I reducethe fluid content of the fabric and so control the amount of appliedresin, preferably by use of a pad mangle although any conventionalequipment will suffice. When a pad mangle is used, the excess fluid isexpressed by nipping the fabric through rollers the nips of which havebeen set at the appropriate pressure to control the amount of resin Foroptimum results, this amount should be such that the weight percentageof resin solution in the regenerated cellulose is not greater than 85%,and ordinarily is between about 60 and The saturated fabric is thenstored in a closed container or batched on a shell and covered to avoiddrying, and held for the critical period, i. e., for more than about 10minutes. At the end of this wet-holding period, the wet fabric is framedto substantially the original greige dimensions and dried to remove thewater. After the drying step the treated fabric is cured in theconventional way to effect polymerization of the resin. Curing may becarried out by passing the fabric over infra-red lamps, passing thefabric through a hot air chamber, or processing in any manner suitablefor the particular conditions. The curing temperatures may varyconsiderably from about 325 to over 400 F. with a correspondingreduction in the time of cure with the increase of temperature.

Illustrative of the utility of my invention is its appli cation to theresin-finishing of rayon marquisette curtain fabrics. Because of theiropen-mesh construction, such fabrics are notoriously dimensionallyunstable when laundered, and many attempts have been made to shrinkproofthem by the application of synthetic resin precondensates. So far as Iam aware, the art has not succeeded in producing a supple, light-weight,regenerated cellulose curtain fabric which will shrink less than about3.5% upon repeated laundering. The accompanying drawings show theproblem which existed with respect to the resintreatment of such fabricsand the solution of the problem provided by my invention.

Fig. 1 is a graph showing the prior art effect of resin application onwarpwise shrinkage and on fabric stiffness (as measured by the meanflexural rigidity as hereinafter defined);

Fig. 2 is a graph showing the effect of my novel finishing process onthe stiffness of fabrics containing large amounts of resin;

Fig. 3 is a graph illustrating the relationship between fabric stiffnessand the amount of applied resin in my fabric and in prior artresin-treated fabrics; and,

Fig. 4 is a graph showing the relationship between fabric stiffness andwarpwise shrinkage on repeated laundering of my fabric and of priorart'resin-treated fabrics.

For the purpose of quantitatively evaluating and comparing the qualitiesof flexibility and suppleness of different fabrics l have selectedfabric stiffness as the physical property which primarily determinesthese qualities. As a measurement of stiffness I have adopted thequantity mean flexural rigidity, sometimes hereinafter abbreviated toMFR. The numerical value of mean I flexural rigidity is equal to thegeometric mean of the flexural rigidity value for the warp and theflexural rigidity value for the'filling, each value being expressed inmilligram-centimeters and computed in the manner described by F. T.Pierce, The handle of cloth as a measurable quantity, The Journal of theTextile Institute, Transactions, vol. 21, page 400 (1939).

Curve 2 of Fig. 1 shows a typical instance of the variation of warpshrinkage with increasing amounts of applied resin. This curve, and allof the graphs of Figs. 1-4, represent test data obtained on anopen-mesh. regenerated cellulose marquisette. The curves of Fig. 1 wereobtained by impregnating the fabric with an aqueous solution of dimethylether of dimethylolurea and zinc chloride as a catalyst, drying at 175F. and curing at 350 F., in accordance with a current commercial 15% isnecessary to reduce the shrinkage to a value of 5 the order of 2% orless.

Curve 4, Fig. '1, illustrates the accompanying increase in fabricstiffness with increasing amounts of resin applied to the same fabric.As this curve shows, application of as much as 15% of resinprecondensate would in crease the stiffness of the fabric to a valuemany times the value for the untreated fabric, and result in a boardyfabric useless for most purposes. It is evident from a consideration ofcurves 2 and 4 that desirable low levels of dimensional stability couldnot be attained by the application of large amounts of resin withoutdestroying the fabrics qualities of flexibility, drapability andsuppleness.

The remarkable result of my new process is graphically illustrated inFig. 2, in which the curves show the decrease in mean flexural rigidityof the cured fabric as the wet-holding time is increased. Curve 6 wasobtained on a fabric in which 22.5% of resin precondensate had beenincorporated; the fabric of curve 8 was similar except that the amountof precondensate applied was 18.0%. Line 10 shows the flexural rigidityof the same fabric untreated. It will be observed from each curve thatthe fabric stiffness is reduced to a level that approximates that of theuntreated base fabric, even with large amounts of applied resin.

The effect of the amount of applied resin is further shown by Fig. 3 inwhich curve 12 shows the rapid increase of fabric stiffness as theamount of resin applied is increased above about 12% in a conventionalprocess. Curve 14 shows the effect of a wet-holding step of 3 hoursduration in a process otherwise the same, as applied to the same fabric,in keeping the mean flexural rigidity at about the same value, line 16,as that of the untreated fabric.

Fig. 4 shows the effect of the wet-holding step on fabric stiflness fordifferent degrees of shrinkproofness of the fabric. Curve 20 representsa fabric of my invention (curve 14) as contrasted with the curve 18 fora prior art fabric (curve 12). Line 22 indicates the mean flexuralrigidity value for the untreated fabric. From these curves it is clearthat the long-sought objective low shrinkage combined with low stiflnesshas been attained.

As shown by curve 4 of Fig. 1, the maximum amount of resin precondensatewhich may be applied to a rayon marquisette fabric by prior-art methods,without substantially destroying its flexibility and suppleness, is lessthan about For heavier-weight fabrics such as are used in suitings,sport shirts, uniforms, and garment interliners, curves similar to curve4 may be drawn but the resin-level at which the fabric stiffnessincreases sharply in the absence of my wet-holding step will generallybe higher than about 15% and lower than about 25% depending primarily onthe particular fabric. For example, with a 48 x 47, 2.85 pounds/yard,regenerated cellulose woven sheeting, I have found that my wetholdingstep may not produce a significant change in fabric properties until theamount of resin precondensate applied is increased to about Although Iam unable to give any formula for predicting precisely the lowerresin-level at which my wetholding step becomes important in theresin-treatment of heavier-weight fabrics, the fact remains that myinvention makes it possible to increase the amount of resinsignificantly beyond this level without destroying the utility of thefabric. Furthermore, the interaction of variables of the process, suchas ambient temperature, humidity, age of the precondensate, and localdifferences within the fabric with respect to resin concentration,variables which are diflicult or impossible for the operator to controlin commercial finishingmake it advisable to employ my wet-holding stepwhenever the amount. of applied resin exceeds about 15%.

The duration of the wet-holding step necessary to produce a commerciallyuseful fabric will vary with the amount and type of resin precondensateapplied, the characteristics of the particular regenerated cellulose,and other variables of the process, but is, I have found, usually longerthan about minutes. Continued improvement in the suppleness andflexibility of the resintreated and cured fabric is obtained in somecases with wet-holding periods as long as three days. When the amount ofapplied resin is near the lower resin-level at which my wet-holding stepbecomes important, generally the duration of the wet-holding steprequired to obtain a given degree of suppleness will be shorter thanwhen the amount of applied resin is greater. The optimum durationrequired by any particular set of conditions can readily be determinedby the skilled operator. Ordinarily this time will be between about onehour and four or five hours.

While it may be possible under some circumstances with relativelyheavy-weight regenerated cellulose fabrics to apply sufficient resin tosecure adequate shrinkage control without using my wet-holding step, theimprovement in other fabric properties obtained by a further incrementof applied resin is remarkable. In the garment interliner field I havebeen able to produce fabrics which are equal, or even superior, increase-resistance t0 the highest quality animal-fiber interliners. Thelarger amounts of resin which may be applied by my process greatlyreduced the water-imbibition capacity of the fabric, although the fabricstill retains a high capacity for transmitting moisture. In shirting orsuiting materials these properties are especially desirable, and suchfabrics treated according to my invention will dry as rapidly as nylonfabrics of similar construction but will not create the clamminessassociated with nylon fabrics because of the low capacity of nylon totransmit moisture away from the body of the wearer.

While my process permits a significant increase in the amounts of resinprecondensate which may be applied to regenerated cellulose fabrics, itis important to point out that these fabrics have an ultimate capacityfor resin which is generally about based on the relative weights of theapplied resin and the untreated regenerated cellulose. The exactcapacity will vary somewhat with the particular fabric and with thevariables of the process. When this ultimate capacity has been exceeded,no amount of wet-holding will sufiice to avoid stiffness.

The following examples of specific ways in which my process may becarried out to produce my novel fabric are given by way of illustrationof my invention and not of limitation thereof:

Example I aqueous solution containing 27.5% of dimethyl ether ofdimethylol urea, and 2.5% of zinc chloride (catalyst). The impregnatedfabric was pressed between squeeze rolls at such a pressure that thesaturated fabric retained a weight of solution equal to about 74% of theoriginal weight of the fabric. A portion (A) of the squeezed fabric wasdried according to conventional practice-i. e., within 2-3 minutes afterimpregnation and cured in an oven at 350 for three minutes; theremainder (B) was batched on a roll, covered to prevent drying, andallowed to stand in a wet condition for 18 hours. The wet fabric wasthen dried in a drying oven at 150 F. for 2 minutes and finally cured inan oven at 350 F. for three minutes.

The mean flexural rigidity of both treated fabric portions, and of anuntreated control sample (C) of the same fabric, was determined. Samples(B) and (C) were then washed in accordance with the Government StandardWash Test, CCC-T191A (Rayon). The mean fiexural rigidity (MFR) values,and the warp shrinkage after each washing are shown in the followingtable:

Example I] A 44 x 30, white regenerated cellulose (viscose) marquisette,which had been bottomed and then dried on a tenter to substantially theoriginal greige dimensions, was impregnated with an aqueous solutioncontaining 35% of dimethylol urea resin (American Cyanamid-Aerotex 450),and 3.2% of zinc chloride (catalyst). The impregnated fabricwas pressedbetween squeeze rolls at a pressure such that the saturated fabric.retained a weight of solution approximately equal to 60% of the originalweight of the fabric and a weight of dimethylol urea resin approximatelyequal to 21% of the original Weight of the fabric. The squeezed fabricwas then batched on 'a roll, covered to prevent drying and allowed tostand in a wet condition for about 17 hours. The wet fabric was melamineand 2.1% of zinc chloride (catalyst).

Un- Samples 1 2 3 4 5 6 treated Fabric MFR 70 78 79 1, 370 23 WarpShrinkage 1.9 1.8 1.1 1.9 1.9 13.3

Example III A 46 x 34, light weight regenerated cellulose (viscose)marquisette, 44" wide, which had been bottomed and dried on a tenterframe to substantially the original greige dimensions, was impregnatedwith an aqueous solution containing 23.6% of water soluble methylatedmethylol- The fabric was pressed between squeeze rolls under a pressuresuch that the fabric retained a weight of solution equal to about 77% ofthe original Weight of the fabric. The wet fabric was then batched on aroll, covered to prevent drying and allowed to stand in a Wet conditionfor 70 hours. The wet fabric was next dried in a drying oven at F. fortwo minutes, and then cured in a curing oven at 350 F. for 3 minutes.

The following table gives the pertinent shrinkage and MFR data, as wellas the mean flexural rigidities determined for otherwise identical runsin which wet-holding times of 3, 8, and 24 hours were employed.

Two samples of a 46 x 34 light weight marquisette 44 inches wide, withnylon filling and regenerated cellulose (viscose) warps, which had beenboarded, bottomed, and dried on a tenter frame to substantially the:original greige dimensions, were impregnated with an aqueous solutioncontaining 30% of dimethyl ether of dimethylol urea and 2.7% of zincchloride (catalyst). The wet fabrics were passed between squeeze rollsat a pressure such that they retained a weight of solution equal toabout 50% of the original weight of the fabric (or about 73% based onthe regenerated cellulose portion of the fabric), then batched on ashell, covered to prevent drying, and allowed to stand (one sample forapproximately 3 hours and the other for 20 hours). The wet samples weredried in a covered tenter at approximately their original greige I foreach of these samples as well as the MFR of the fabric identicallytreated except for the omission of my wetholding step.

r about 22% based on the regenerated cellulose.

Example V A sample of a 46 x 32 regenerated cellulose (viscose)marquisette, 44 inches wide, which had been bottomed and dried on atenter frame to substantially the original greige dimensions wasimpregnated with an aqueous resin solution containing 40% of dimethylether of dimethylolurea and-3.6% of zinc chloride (catalyst). Theimpregnated fabric was pressed between squeeze rolls at a pressure suchthat the saturated fabric retained a weight of solution equal to about60% of the weight of the tion containing 40% of water solublemethylolmelamine and 2.4% of an acid-forming catalytic agent produced byMonsanto Chemical Company and sold under the trade name AC. The fabricwas squeezed so as to retain a weight of solution approximately equal to57% of the original weight of the fabric. Following the squeezing step,the Wet saturated fabric was batched on a shell, covered to preventdrying, and allowed to stand for approximately hours. The wet fabric wasthen dried in a covered tenter at 150 F. for 2 minutes and finally curedin an oven at 350 F. for about three minutes. The fabric had acommercially satisfactory flexibility and suppleness for use as curtainmaterial and a shrinkage less than 2%. The same base fabric whenidentically treated except for the omission of my wet-holding step, wasobjectionably stiff and boardy.

Example VII A composite cotton-viscose rayon fabric (garment interlinerfabric) in the greige, consisting of 31.5/1 cotton warps, 64 sley, and7/ 1, 3 denier rayon fillings, 38 pick, and weighing 0.46 pound peryard, was desized, framed to 40 inches and dried. The fabric was thenimpregnated with an aqueous solution containing the followingingredients: dimethyl ether of dimethylol urea about original fabric,then batched on a roll, covered to prevent zinc hl ide abo t 3.2 percentand a ll amou t of drying, and allowed to stand in 21 wet condition forabout pigment dyes, Following impregnation, the fabric was 3 hours. Thewet fabric was then framed to substanpressed between squeeze rolls sothat it retained a weight tially the Original greige dimensions anddried in a y g of solution equal to about 70% of the Weight of theorigioven at 160 F. for about one-half minute. Thereafter, nal fabric,then batched on a roll, covered to prevent the treated fabric was curedin a curing oven at about evaporation, and allowed to stand in a dampcondition 340 F. for three and one half minutes. The cured forapproximately 48 hours. The wet fabric was then sample was washed withan untreated control of the same framed to a width of inches, dried in adrying oven material in accordance with the Government Standard at 260F. for about 2 minutes and then cured in a curing Wash Test,CCCTl9lA'(Rayon). The original flexioven at 340 F. for five minutes. Thecured sample was bility and suppleness of the two fabrics as measured by0 thereafter treated with a 6% aqueous solution of amthe mean flexuralrigidity (MFR) and the dimensional monia, allowed to stand in a dampcondition for 3 hours, stability of the warp and filling after eachwashing, exjig washed first in cold water and then in warm water atpressed as percent, are shown in the following table 140 F., againframed to a width of 40 inches and dried. wherein W indicates warpwiseand F weftwise shrink- 40 The finished sample was washed with anuntreated control age: sample of the same fabric in accordance with theStandard Shrinkage, Percent Resin Samples Pickup, MFR 1st Wash 2nd Wash3rd Wash 4th Wash 5th Wash Percent W F W F W F W F W F Treated Fabric 240.0 *0.3 0.7 0.0 0.8 m 0 0 L1 Untreated Fabric 0.0 23 13.6 11.9 13.411.7 11.4 11.7 18.3 13.4 13.9 12.4

Dimensional increase.

Government Wash Test CCCT-191A (Rayon). The original flexibility andsuppleness of the two fabrics as measured by the mean flexural rigidity(MFR) and the dimensional stability of the warp and filling after eachwashing, expressed as percent, are shown in the following curtain fabric4-4" wide, which had been bottomed and 00 table:

Shrinkage, Percent Resin Fabric Pickup, MFR 1st Wash 2nd Wash 3rd Wash4th Wash 5th Wash Percent W F W F W F W F W F Dimensional increase.

then dried on a tenter frame to substantially the original The meanflexural rigidity value of 321 shown in the greige dimensions, wasimpregnated with an aqueous soluabove table compares with an MFR valueof 1810 for the same base fabric when identically treated except for theomission of my wet-holding step.

Example VIII A sample of a 46 x 32 regenerated cellulose (viscose)marquisette 44 inches wide, which has been bottomed, and dried on atenter frame to substantially the original greige dimensions, wasimpregnated with an aqueous solution containing 40% of dimethyl ether ofdimethylol urea and 3.6% zinc chloride (catalyst). The wet fabric waspassed between squeeze rolls at a pressure such that it retained aweight of solution equal to about 60% of the weight of the originalfabric, then batched on a shell, covered to prevent drying, and allowedto stand in a wet condition for 31 minutes. Thereafter the wet samplewas framed to substantially the original greige dimensions and dried ina covered tenter at 150 F., for two minutes, and then cured in a curingoven at 350 F. for about three minutes. The cured samples were washed,with an untreated control sample of the same fabric, in accordance withthe Government Standard Wash Test, CCC-T-191A (Rayon). The originalflexibility and suppleness of the two fabrics as measured by the meanflexural rigidity (MFR) and the warp shrinkage after each washing,expressed in per cent, are shown in the following table, which alsoincludes, for comparison, the MFR of the same base fabric whenidentically treated except for the omission of my wet-holding step.

In all of the foregoing examples the fabric was framed to substantiallyits original greige dimensions after the wet-holding step andimmediately before drying.

The present application is a continuation-in-part of my priorapplication, Serial No. 78,414, filed February 25, 1949, and nowabandoned.

I claim:

1. The process of treating a textile material containing regeneratedcellulose to render it dimensionally stable to repeated laundering,reduce its water imbibition capacity and greatly increase its resiliencewhile preserving substantially unimpaired the flexibility and supplenessof the untreated material as measured by its mean flexural rigidity,which comprises impregnating the material with an aqueous solution of anacidic, readily-cold-water-soluble polymerization catalyst and anessentially monomeric resin precondensate selected from the classconsisting of dimethylol urea, the lower alkylolmelarnines, the loweralkyl ethers of dimethylol urea and the lower alkyl ethers of the loweralkylolmelamines, squeezing the impregnated material to leave in thematerial an amount of the solu tion no more than sufficient to provideon the regenerated cellulose up to a limit of about 85% of solution andan amount of the resin precondensate within the range from about toabout 35%, both based on the weight of the regenerated cellulose,maintaining the squeezed impregnated material in a wet condition at roomtemperature for a period of from about 10 minutes to about 3 days, andthereafter drying the material and subjecting the dried material to acuring temperature to convert the resin precondensate to Water insolublecondition, the amount of resin fixed in the material being significantlygreater than the least amount which would cause the material aftercuring to be objectionably stiff in the absence of the step ofmaintaining the material in a wet condition.

2. A process according to claim 1, inwhich the resin precondensate isdimethylol urea.

3. A process according to claim 1 in which the resin precondensate is alower alkylolmelamine.

4. A process according to claim 1 in which the resin precondensate is alower alkyletherof dimethylol urea.

5. A process accordingto claim 1 in which the resin precondensate is alower alkyl ether of a lower alkyl melamine.

6. A process according to claim 4 in which the regenerated cellulose isviscose.

7. A process according to claim 4 in which the polymerization catalystis an acid salt.

8. A process according to claim 4 in which the polymerization catalystis an acid salt selected from the class consisting of ammonium chloride,zinc chloride, and diammonium phosphate.

9. A process according to claim 4 in which the squeezed impregnatedmaterial is maintained in a wet condition for a period of at least onehour.

10. A process according to claim 4 in which the curing temperature isbetween about 325 F. and about 400 F.

11. The method of treating a textile sheet material containing celluloseregenerated from viscose to render said sheet material dimensionallystable to repeated laundering, reduce its water-imbibition capacity andgreatly increase its resilience while preserving substantiallyunimpaired the flexibility and suppleness of the untreated materialwhich comprises impregnating the material with an aqueous solution of apolymerization catalyst selected from the group consisting of ammoniumchloride, zinc chloride, and diammonium phosphate, and an essentiallymonomeric lower alkyl ether of dimethylol urea, squeezing theimpregnated material to leave in the material a weight percentage ofsolution no more than sufficient to provide on the regenerated celluloseup to a limit of about of solution and an amount of the lower alkylether of dimethylol urea within the range from about 15% to about 35%,both by Weight of the regenerated cellulose, maintaining the squeezedimpregnated material in a wet condition at room temperature for a periodfrom about one hour to three days, and thereafter drying the materialand subjecting it to a curing temperature between about 325 F. and 400F., the amount of resin fixed in the material being significantlygreater than the least amount which would cause the material aftercuring to be objectionably stiff in the absence of the step ofmaintaining the material in a wet condition.

12. The process of claim 1 wherein the textile material consists ofcotton and regenerated cellulose.

13. The process of claim 1 wherein the textile material consists ofregenerated cellulose.

14. A supple, highly resilient, resin-treated textile sheet materialcontaining regenerated cellulose, said material having been impregnatedwith an aqueous solution of an acidic readily-cold-water solublepolymerization catalyst and an essentially monomeric resin precondensateselected from the class consisting of dimethylol urea, the loweralltylolmelamines, the lower alkyl ethers of dimethylol urea and thelower alkyl ethers of the lower alkylolmelamines, to leave in thematerial an amount of the solution no more than suflicient to provide onthe regenerated cellulose up to a limit of about 85 of solution and anamount of the resin precondensate within the range from about 15% toabout 35%, both based on the weight of the regenerated cellulose, thematerial thereafter having been maintained in a wet condition at roomtemperature for a period of from 10 minutes to about 3 days, and thematerial thereafter having been dried and the resin cured, the amount ofresin fixed in the material being significantly greater than the leastamount which would cause the material after curing to be objectionablystifi in the absence of the step of maintaining the material in a wetcondition, and sufiicient to render the material dimensionally stable torepeated laundering, the

, 11 material having a reduced water-imbibition capacity, greatlyincreased resilience and substantially the flexibility and suppleness ofthe untreated material as measured by its mean flexural rigidity.

References Cited in the file of this patent UNITED STATES PATENTS2,055,322 Teller Sept. 22, 1936 Lippert Feb. 21, 1939 Widmer Oct. 29,1940 Auer May 20, 1941 Thackston Dec. 23, 1941

1. THE PROCESS OF TREATING A TEXTILE MATERIAL CONTAINING REGENERATEDCELLULOSE TO RENDER IT DIMENSIONALLY STABLE TO REPEATED LAUNDERING,REDUCE ITS WATER IMBIBITION CAPACITY AND GREATLY INCREASE ITS RESILIENCEWHILE PRESERVING SUBSTANTIALLY UNIMPAIRED THE FLEXIBILITY AND SEPPLENESSOF THE UNTREATED MATERIAL AS MEASURED BY ITS MEAN FLEXURAL RIGIDITY,WHICH COMPRISES IMPREGNATING THE MATERIAL WITH AN AQUEOUS SOLUTION OF ANACIDIC, READILY-COLD-WATER-SOLUBLE POLYMERIZATION CATALYST AND ANESSENTIALLY MONOMERIC RESIN PRECONDENSATE SELECTED FROM THE CLASSCONSISTING OF DIMETHYLOL, UREA, THE LOWER ALKYLOMELAMINES, THE LOWERALKYL ETHERS OF DIMETHYLOL UREA AND THE LOWER ALKYL ETHER OF THE LOWERALKYLOLMELAMINES, SQUEEZING THE INPREGNATED MATERIAL TO LEAVE IN THEMATERIAL AN AMOUNT OF THE SOLUTION NO MORE THAN SUFFICIENT TO PROVIDE ONTHE REGENERATED CELLULOSE UP TO A LIMIT OF ABOUT 85% OF SOLUTION AND ANAMOUNT OF THE RESIN PRECONDENSATE WITHIN THE RANGE FROM ABOUT 15% TOABOUT 35%, BOTH BASED ON THE WEIGHT OF THE REGENERATED CELLULOSE,MAINTAINING THE SQUEEZED IMPREGNATED MATERIAL IN A WET CONDITION AT ROOMTEMPERATURE FOR A PERIOD OF FROM ABOUT 10 MINUTES TO ABOUT 3 DAYS, ANDTHEREAFTER DRYING THE MATERIAL AND SUBJECTING THE DRIED MATERIAL TO ACURING TEMPERATURE TO CONVENT THE RESIN PRECONDENSATE TO WATER INSOLUBLECONDITION, THE AMOUNT OF RESIN FIXED IN THE MATERIAL BEING SIGNIFICANTLYGREATER THAN THE LEAST AMOUNT WHICH WOULD CAUSE THE MATERIAL AFTERCURING TO BE OBJECTIONABLY STIFF IN THE ABSENCE OF THE STEP OFMAINTAINING THE MATERIAL IN A WET CONDITION.